Comment 9 for bug 1194579

Reviewed: https://review.openstack.org/142101
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=79c97120de9cff4d0992b5d41ff4bbf05e890f89
Submitter: Jenkins
Branch: master

commit 79c97120de9cff4d0992b5d41ff4bbf05e890f89
Author: Ann Kamyshnikova <email address hidden>
Date: Fri Dec 12 15:30:06 2014 +0300

    Default security group table

    This change prevents the race condition by enforcing a single default
    security group via new table default_security_group. It has tenant_id
    as primary key and security_group_id, which is id of default
    security group. Migration that inroduces this table has sanity check that
    verifies that there is no duplicate default security group in any
    tenant.

    This idea has come up from discussion in comments to
    https://review.openstack.org/135006

    DocImpact

    Closes-bug: #1194579

    Change-Id: Ifa8fbddd22bce4c50836cf443ebe10dff37443ef